Fuel pump



April 3, 1934. E. o. P. THr-:GE Er AL 1,953,449

FUEL PUMP Filed Jan..9, 1953 2 sheets-sneer 1 l .f. '6" l77/@36- t, H- G-Cmmegmom April 3', 1934. E. o. Pf HEG Er A1.

FUEL PUMP Filed Jan. 9, ms 2 sheets-sheet 2 50 gine.

'Patented Apr.4 3, 1934 f vUNITED STATES PATENT? OFFICE FUEL 'PUMr ,Eavin ossian Parcival Thege, stockholm, and

Hilding Gunnar Camner, Bergland, Ektorp,

Sweden, assignors to Aktiebolaget Atlas Diesel, Stockholm, Sweden, a. corporation of Sweden Application In slide valves, especially of fuel pumps for internal combustion engines, in which the fuel. is subjected to a very great pressure during thev injection, it isnecessary that t c tightness of the slide valve is effective, so' that Ino fuel necessary for the working stroke of the engine piston gets lost. This invention relates to a simple arrangement, through which the surface closure between the slide valve andits`casing is doubled, trebled and -so on, which results in the escaping of the fuel between the slide valve and its casing being rendered highlydifcult or entirely impossible. Theinvention may be applied also to plungers or pistons of for instance fuel pumps operating simultaneously as slide valves.

Some forms of execution of the invention are shown as examples in the accompanying drawings. Figs. lgand 2 are vertical sections of fuel pumps in which the pump plunger operates also as a slide valve. Fig. 3 shows in a vertical section a pump for internal combustion engines and provided with a turnable working plunger which operates also as a slide valve controlling the supply of fuel. Fig. 4 is a section on the line A-B in Fig. 3. Fig. 5 shows in a vertical section a fuelpump `provided Iwith a controlling slide valve arranged in accordance with the invention. Fig. 6 is a section on the line `C--D4 of Fig. 5. 1, Fig. 1, is the driving shaft of the pump.

The said shaft, is provided with a cam disc 2, which during the rotary motiony of the shaft acts upon a roller 3, provided in a plunger 5, which by a spring 4 is forced towards the cam disc.

' The plunger 6 of the fuel pump is .forced downwards duringthe suction stroke by a spring '7 and its motion is stopped by an arm 9, which is swingable on a pin 8 and may be. brought into different positions vertically by an eccentric 10, adjusted manually or by a governor, not shown.

11 is the fuel supplying conduit, 12 the suction I valve and 13 the delivery valve leading to the'l combustion chamber of the engine cylinder.

During' its downward stroke the plunger 6 sucks fuel into the pump chamber 14 in a quantity determined by the stop arm 9. As the plunger 5 is then vforced'upwards by the cam disc 2 and enters into contact with the plunger 6, the

` latter forces the fuel through the valve 13 and further to the combustion chamber of the en- The --fuel superfluous for the working stroke of the engine piston is discharged through a channel 15 leading" to the fuel supplying conduit 11.

For this purpose a channel 16 is provided in the plunger 6 andcommunicates through side January 9,1933, serial No. 650,944 1n sweden .my 11, 1932 2 claims. (o1. 10s- 41)l 'openings 17 with a groove or recess 18 made in the plunger' and preferably extending round the same. For improving the tightness between the plunger Vand the pump casing, a second groove 19, according to thisinvention, is pro- 6o vided in the outer side of the plunger, with which co-operates a groove 20 in the pump casing. The said groove 2,0 has such a position, that, as the plunger 6 is in its lowermost position shown in Fig. 1, which is assumed to be the' 65 normal position at the end of the suction stroke of theplunger, the groove 19 is located opposite tothe groove 20 and the distance :r between thetop edge of the groove 18 and the lower edge of the groove 20 lis 'equal tothe distance :c between 70 the top edge of the groove 19 and the channel 15.

As ythe plunger 6 is moved upwards through the distance x; fuel is forced into the combustion c chamber. As the plunger. 6 is moved further upwards, the groove 18 enters-into communication 75 with the chamber constituted by the grooves 19 and 20, which in its turn enters into communication with the channel 15 through. the groove l19, so that fuel ows through channel 16, groove 18, grooves 19 and 20 and nally into the chan- 80 nel 15. Through the provision of the grooves 19 and-20 a double surface closure between theplunger V6 and the pump casing is gained, the escaping of fuel being thereby rendered diilicult or impossible. A 85 The said surface closure may, evidently, be still more increased through the provision of one or more additional grooves in the plunger and the pump casing'. 'Ihus in Fig. 2 two pairsI of co-operating grooves 21, 22 and 23, 24 are shown, 90 which are so located, that at the normal lower position of the plunger 25 the`distances a: are` equal. Consequently, in the pump now in question there are three closing places between the groove 26 of the plunger and the discharge chan- 95 nel- 2'7 for the superiiuous fuel. Plunger 25 of the pump is moved upwards and downwards by an eccentric 29, strap 30 and rod 31.

In Figs. 3 and 4 the inventionis shown applied to a plunger 32 acting also as a controlling slide 100 valve, and sgi arranged, that the plunger, turned into differentHpositions controls the. quantity of returning fue/1 superuous for the working stroke of the engine piston. 33 is the fuel inlet of the pump chamber 34.A The lsaid inlet has no valve, so that fuel rushes into the chamber, as the inlet is uncovered by the plunger 32 during its suction stroke. 3'? is a spring actuated delivery valve leading to the combustion chamber of the engine. Fuel superuous for the workingstroke of the 1910 engine `piston returns to the supply of fuel through a channel 38. Plunger 32, sliding in the lining 39 of the pump, is moved upwards by acam disc 40 provided on the driving shaft 35 of 'the pump. Thesaid cam discacts upon a plunger 41, provided with a head 42, against which the lower end of the plunger 32 is forced by a spring 43, bearing .against a ring 44 on the plunger and at its top end against a ring 45. A worm wheel 46 is journaled on the pump lining 39, between the ring and an offset in the pump frame, and meshes with' a screw spindle 47 journaledy in the said frame. The said screw spindle may be rotated manually, for instance by means of a crank (not shown) or by a governordriven by the engine. 'I'he said governor may be of the centrifugal type and the means transmitting the motion from the governor to the screw spindle may be of any suitable or conventional construction. Two arms 48 extend downward from the worm wheel 46 and l engage lateral projections 49 provided on the plunger 32,l so that the latter is rotated together with the worm wheel 46 and thus may be turned into different positions.

v A channel 50 in the plunger 32 communicates through radial openings with a groove or recess 51 provided in the outer side of the plunger at the lower end of the same. lThe said recess 51 has a special shape and extends upwards like a wedge along the plunger, so that a slanting boundling wall 52 is effected, constituting an overflow edge for superfluous fuel. Nearer to the top end of the plunger a groove or recess 53 is provided in the plunger surface, which has substantially the same shape and the same position relatively to the plunger as the recess 51' and constitutes an overflow edge 54.' The said recess 53 co-operates with a groove 55 in the lining 39. As the plunger 32 is turned into different positions either parts of the overow edges 52 and' 54 respectively located at a higher level arrive first to the recess 55 and the outlet channel 33 respectively during the upward stroke of the plunger, so that the escaping of superfluous fuel starts at an earlier moment, the quantity of discharged fuel being there- (by increased, or lower partsof the overflow edges 52 and 54enter rst into action, which results in the quantity of the discharged fuel being reduced. e

Consequently also inthe pump illustrated in Figs. 3 and 4 the surface closure on the distance between the groove 51 and the channel 38 for the superfluous fuel is doubled. Through the provision of a still greater number of recesses the surface closure is accordingly multiplied.

The invention may, evidently, 'be applied also to members acting only as a controlling slide valve. Fig. 5 shows a fuel pump provided with a controlling slide valve arranged in accordance with this invention.-

The plunger Y56 of the pump` forced by a spring 57 against a plunger 61, which' isslidably mounted in the pump frame 58 and acted upon by an eccentric 59 on the driving shaft 60 of the pump (in accordance with Fig; 2). Plunger 56 csucks fuel into the pump chamber 62 from the fuel supplying conduit 63jand through a valve 64 and channel 65 and forces during its working stroke the fuel through the delivery valve 66 to the combustionchamber of the engine.l 67 is a return conduit for fuel-superfluous for the working stroke of the engine piston. The amount of the returning superfluous fuel is controlledby a slide valve 68, which is arranged substantially in the same manner as the slide valve 32, Fig. 3, operating also' as a plunger Thus two wedge shaped grooves or recesses 69 and 70 are provided in the side of the slide valve', which extend upwards and 'constitute slanting overflow edges 71 and 72 respectively.` A groove or recess 73 is provided in the pump casing at the groove 69, and the groove communicates uninterruptedly with a channel 74 leading to-the fuel, supplying conduit 63. The slide valve 68 is connected to therplunger 61 in a turnable mannerl and is moved upwards and downwards by the same. The slide valve 6 8 may be turned into different positions by means of a hand lever 75,

which bears against the pump frame and an arm 76 and engages a part 77 of the slide valve 68, for instance square in cross section.

f' By turning the slide valve 68 into different positions, a part of the overflow edge 71 located at a higherA or lower level will arrive to the channel 67 at an earlierv or later moment, while a corresponding part of the overflow edge 72 arrives simultaneously tothe lower edge of the recess 73. In this manner a return passage for the superfluous fuel is effected viz. channel 67, chamber 69, 73,l groove 70 and channel 74, v which passage is opened at an earlier or later moment in accordance with the position of the slide valve 68 pe- 7ripherally.

The channels and openings of the slide valve or the plunger or piston of the fuel pump operating as a slide valve and the casing of the same may evidently be arrangedin other manners' than shown in the drawings and described above with,- out exceeding lthe limits of the invention.

vWe claim: y A

1. In na fuel pump for internal combustion engines arranged for discharging fuel superfluous for the working stroke of the engine piston, a casing having a pump chamber, a discharge passage for the superfluous fuel, a member reciprocally mounted in saidJcasing, said member having a plurality of recesses forming axially spaced slide valve surfaces. thereon, said casing having recesses corresponding to the recesses of said member, the axial extent of said recesses being greater than the stroke of said reciprocable member and the axial extent of the said slide vlave surfaces, and a passageway between the pump chamber and the discharge passage constituted-in part by all of said recesses and controlled bysaid slide valve surfaces.

2. A fuel pump as claimed in claim 1, characterized in that a bounding wall of one of the recesses is oblique with respect to. the axis of move-u ment of said member whereby the latter may be turned to `vary the quantity of fuel discharged.

EDVIN OSSIAN PARCIVAL THEGE. vIHZILD'IIIGr GUNNAR CAMNER..

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